This disclosure relates in general to a computer system and more specifically to controlling a change in the power state of computer system.
Computer systems are information handling systems which can be designed to give independent computing power to one user or a plurality of users. Computer systems may be found in many forms including, for example, mainframes, minicomputers, workstations, servers, personal computers, internet terminals, notebooks, and embedded systems. Computer systems include desk top, floor standing, rack mounted, or portable versions. A typical computer system includes at least one system processor, associated memory and control logic, and a number of peripheral devices that provide input and output for the system. Such peripheral devices may include display monitors, keyboards, mouse-type input devices, floppy and hard disk drives, CD-ROM drives, printers, network capability card circuits, terminal devices, modems, televisions, sound devices, voice recognition devices, electronic pen devices, and mass storage devices such as tape drives, CD-R drives, or DVDs.
Attempts by the computer industry to reduce the amount of power consumed by computer systems has led to power management strategies that shut down or turn off various devices and features of the computer system via hardware or software mechanisms when the computer system is not in use. An example of one power management strategy is the ADVANCED POWER MANAGEMENT (APM) Interface Specification, developed by INTEL(trademark) and MICROSOFT(trademark). Another is the ADVANCED CONFIGURATION AND POWER INTERFACE (ACPI) specification by INTEL(trademark), MICROSOFT(trademark), and TOSHIBA(trademark). These specifications define power states at which the computer system may reside. The power states of a power management strategy typically range from the highest state, where the computer system is operating normally in an on power state such as where the computer system can process data, to the lowest state where the computer system is completely turned off. Various devices of the computer system are shut down and the system processor may not perform computations at lower intermediate power states. Such intermediate power states include the Standby, Suspend, and Hibernation power states for the APM specification and the Sleeping and Soft-off power states for ACPI specification.
Computer systems typically include computer busses that allow for the intercoupling of computer system devices such as peripheral devices, system processors, and memory. One type of computer bus is a computer bus conforming to the PCI Local bus standard, rev. 2.2 (PCI rev. 2.2 standard). Computer busses such as those conforming to the PCI rev 2.2 standard may include computer card slots for receiving computer cards having circuitry allowing for computer devices, located on the card, to be added to the computer system.
Installing a computer card with a computer system in an on power state can cause serious damage to the computer system and to the computer card circuit. During installation, a computer card may be xe2x80x9crockedxe2x80x9d into a card slot connector wherein some pins of the computer card may contact corresponding slot connector pins before other pins of the computer card contact their corresponding slot connector pins. Such a situation may momentarily leave a card device ungrounded while receiving power. Another problem is that pins of the computer card may inadvertently contact non corresponding pins of the card slot connector. Consequently, power pins of the slot connector may be connected to signal lines of the device and vice versa. Accordingly, computer systems are typically in a power state where power is removed from the slot connector before a computer card is installed.
The PCI rev. 2.2 standard specifies a power management event (PME#) power management signal that allows a device connected to the bus to send a request to change the power state of the computer system such as to place the computer system in a working power state from another power state such as a sleeping power state or soft-off power state. An example of a circuit configuration utilizing the PME# signal is shown in FIG. 10 of the PCI BUS POWER MANAGEMENT INTERFACE SPECIFICATION, Revision 1.1 and described in the text associated with the Figure. The PCI rev. 2.2 standard also specifies an auxiliary power signal referred to as 3.3 Vaux signal. The 3.3 Vaux signal is active even when the computer system is in a soft-off power state or in a sleeping power state. Because pins of a card and a card slot connector may become cross-connected during installation, inserting a PCI rev. 2.2 compliant computer card into a corresponding PCI rev. 2.2 compliant card slot during a sleeping power state may cause a computer system to change power states due to pins of the computer card shorting a grounded pin of the card slot connector with the PME# signal pin of the card slot connector. Having a computer system change power states due to the insertion of a computer card may lead to customer complaints or damage to the computer card circuit or computer system.
It has been discovered that preventing a computer system from transitioning to a higher power state from a lower power state when a computer system chassis is open advantageously prevents a computer system from inadvertently transitioning to an on power state from a lower power state during the operable coupling of a computer card circuit to a computer bus.
In one aspect of the disclosure invention, a computer system includes at least one connector. Each connector is configured to be coupled to a respective computer card circuit to provide a power management signal from the computer card circuit indicating a request to change a power state of the computer system. The computer system also includes a chassis detection circuit having an output to provide an indication signal of whether a chassis of the computer system is open or closed. The computer system further includes a gating circuit operably coupled to the chassis detection circuit to receive the indication signal from the chassis detection circuit and operably coupled to the at least one connector. The gating circuit has an output selectively provide, as determined by the indication signal, a gated power management signal to initiate the placement of the computer system in a higher power state from a lower power state is response to receiving a power management signal from the at least one connector. The gating circuit provides the gated power management signal when the indication signal indicates that the chassis is closed. The gating circuit does not provide the gated power management signal when the indication signal indicates that the chassis open.
In another aspect, the invention includes a method for controlling a change in a power state of a computer system. The method includes receiving a request signal from a computer card circuit connector to change the power state of a computer system and determining whether the chassis is open or closed. The method also includes preventing the request signal from placing the computer system in a higher power state if the chassis is determined to the open.
In another aspect of the invention, a computer system includes a chassis detection circuit having an output to provide an indication signal of whether a chassis of the computer system is open or closed. The computer system also includes means for preventing a power management signal provided by a computer card circuit connector from changing a power state of the computer system to a higher power state from a lower power state when the indication signal indicates that the chassis is open.
In another aspect of the disclosure, a computer system includes at least one computer bus and a plurality of computer devices. Each computer device is operably coupled to one of the at least one computer bus, and each computer device has an output to provide a power management signal to change a power state of the computer system. The computer system also includes a chassis detection circuit having an output to provide an indication signal of whether a chassis of the computer system is open or closed and a gating circuit coupled to the outputs of the plurality of computer devices to receive the power management signals coupled to the chassis detection circuit to receive the indication signal. The gating circuit has an output to provide a gated power management signal to initiate a change in the power state of the computer system in response to receiving a power management signal from one of the computer devices. The gating circuit does not provide the gated power management signal to change the power state of the computer system to a higher power state from a lower power state when the indication signal indicates that the chassis is open.
In another aspect of the disclosure, a computer system includes a chassis detection circuit having an output to provide an indication signal of whether a chassis of the computer system is open or closed. The computer system also includes a gating circuit operably coupled to the chassis detection circuit to receive the indication signal from the chassis detection circuit. The gating circuit has at least one input to receive a PME# signal. The gating circuit has an output to selectively provide, as determined by the indication signal, a gated power management signal to initiate the placement of the computer system in a higher power state from a lower power state in response to receiving a PME# signal. The gating circuit provides the gated power management signal when the indication signal indicates that the chassis is closed. The gating circuit does not provide the gated power management signal when the indication signal indicates that the chassis open.